Marking or identifying the source or manufacturer of an antenna has generally relied on the antenna's outward features, such as shape, size, color, and package, or through the use of a trademark or a trade dress. Such features or designs may disappear due to wear and tear as time passes, making identification of the source or manufacturer of an antenna difficult. Further, an antenna used in the field, for example, installed on the top of a wireless tower, does not allow easy access for close inspection of the antenna type.
Reflectometry is a measurement technique that has been widely used to diagnose problems associated with radio frequency (RF) antennas or an electronic circuit or device. For example, reflectometry can be used to detect fault, locate disruption, and calibrate distance in a test circuit. Reflectometry includes time-domain, frequency domain, and noise domain analysis. In reflectometry, a test signal, often a wideband or swept-frequency signal, is sent into an electronic circuit or device and a reflected signal is measured at an antenna interface port. Besides reflectometry, transmissometry is another diagnostic tool. But unlike reflectometry that measures a reflected signal, transmissometry measures a transmitted signal.
To detect a faulty antenna, reflectometry measures a maximum return loss and/or a minimum return loss of an antenna. A return loss of a device measures the ratio of an output signal power to an input signal power in decibel. Abnormal maximum/minimum return losses can be useful in detecting an antenna that is not working properly, for example, reflecting signals excessively. However, for working antennas, the measured maximum/minimum return losses are generally within a normal range and do not possess unique features that are suitable for identification purposes. Other than the maximum/minimum return loss, a working antenna generally exhibits random electric behavior, therefore does not have an electronic “signature.”
The present application discloses advantageous methods and devices that can be used to electronically mark and identify an antenna.